Unfortunately, the only solution is possibly to increase your grout joint size to stretch them into the corner. In 59" span that probably equates to a pretty minuscule amount.

Have you already purchased the tile? There are larger format subways that eliminate the amount of grout with a 3x6, making maintenance in the long run much easier.

Select another tile that has a 3x6 Bullnose instead.

@Skippack, how does that solve the dilemma?

If you mean to say purchasing the 3x6 coordinating bullnose and installing in lengthwise to finish the outside edges that would solve the issue. If so, then providing an explanation of how the bullnose is to be used would give McKenna an option to solve her issue.

The OP mentions a bullnose that's 2" wide (it's either a 2x8 or a 2x6 with the finished long side) and she need to cover about another inch; so, if she selects a bullnose that 3" wide instead that should solve her issue.